Quality of Service (QoS) generally relates to the operation of determining transmission rates, error rates, and other characteristics associated with a network service, to the extent they can be measured, and to guarantee such characteristics in advance. In some embodiments, QoS policies allow packets to be prioritized at specific network nodes. For example, when a high-priority is being passed through a network node, the network node may forward these higher priority packets prior to forwarding other lower priority packets by withholding the lower priority packets or putting the high-priority packets in certain high-priority queues.